Method for elimination of reversal reexposure in processing photographic elements



United States Patent 3 246,987 METHOD FOR ELIMINATION 0F REVERSAL RE-EXPOSURE IN PRUCESSING PHOTQGRAPHIC ELEMENTS Wesley T. Hanson, Jr., andHoward W. Vogt, Rochester,

N.Y., assignors t0 Eastman Kodak Company, Rochester, N .Y., acorporation of New Jersey No Drawing. Filed July 11, 1962, Ser. No.209,263

9 Claims. (Cl. 96-5?) This invention relates to an improved method ofphotographic processing, and more particularly, to the reversalprocessing of photographic silver halide emulsions.

It is known that in the processing of photographic silver halideemulsions of color films, the exposed emulsions can be subjected to afirst (negative) developer which is a conventional black-and-whitedeveloper, followed by reversal re-exposure and subsequent colordevelopment.

Elimination of the reversal re-exposure step in processing photographicsilver halide emulsions is a desirable improvement, particularly formultilayer color elements. Certain nucleating agents that have been usedin alkaline solutions after the first development and before the colordevelopment in place of the reversal re-exposure step have not been asstable as desired at the pI-Is required in the color developer forcertain photographic color elements that contain incorporatedcolor-forming couplers in the silver halide emulsion layers.

It is, therefore, an object of our invention to provide nucleatingagents which have good stability in aqueous processing solutions atpI-Is from 2 to 14.

Another object is to provide an improved nucleating bath for use inplace of reversal re-exposure.

Another object is to provide a stable reversal color developer solutioncontaining our nucleating agent which nucleates unexposed silver halideand then immediately color develops the nucleated silver halide toproduce the corresponding color images.

These and still other objects which will become apparent from thefollowing specification and claims are acomplished by use of ourinvention.

Acording to the method of our invention, the reversal re-exposure forthe reversal processing of photographic color reproductions iseliminated by treating the photographic silver halide emulsion after afirst (negative) development with an aqueous solution of a boroncompound which has at least one and not more than three hydrogen toboron bonds. These boron compounds include the boranes and theborazines. In one embodiment of our invention, these boron compounds areused as nucleating agents in an aqueous nucleating bath after thenegative development and before the color development. In anotherembodiment of our invention, these boron compounds are used asnucleating agents in the color developer solution so that no separatenucleating bath is required. In the process of nucleating the negativelydeveloped photographic element, the previously unexposed and undevelopedsilver halide grains are nucleated, that is, rendered developable uponcontact with a color developing agent without being exposed to light. Inthe process of nucleation, no appreciable silver image is produced inthe silver halide emulsion layers. However, as soon as the silver halideis nucleated, it is developable upon contact with the color developer toproduce a silver and a color image. Thus, when the nucleating agent isincorporated in the color developer, a silver and a color image formsrapidly upon nucleation.

Included among the boron compounds used to advantage as nucleatingagents are those of the formula:

(I) ZBI-I in which Z represents ammonia, an amine, such as analkylamine, for example, methylamine, dimethylamme,

trimethylamine, ethylamine, ethanolamine, diethylamine, triethylamine,diethanolamine, propylamine, 3-hydroxypropylamine, dipropylamine,tripropylamine, primary-butylamine, secondary-butylamine,tertiary-butylamine, primary-amylamine, secondary-amylamine,tertiary-amyL amine, etc., a polyarnine, for example, ethylenediamine,Z-aminoethylamine borane, etc., an aromatic amine, for example, aniline,etc., a cyclic amine, for example, pyridine, 2,6-lutidine, 3,4-1utidine,2,4-lutidine, Z-ethylpyridine, 2,4-diethylpyridine, 2,6-diethylpyridine,3,4-diethylpyridine, 2-propylpyridine, 4-propylpyridine,3-propylpyridine, etc., a hydrazine borane, a phosphine, such as analkylphosphine, for example, methylphosphine, dimethylphosphine,trimethylpliosphine, ethylphosphine, diethylphosphine,triethylphosphine, propylphosphine, dipropylphosphine,tripropylphosphine, primary-butylphosphine, secondary-butylphosphine,etc., an aryl phosphine, for example, phenylphosphine, etc., an arsine,such as an alkylarsine, for example, methylarsine, dimethylarsine,trimethylarsine, propylarsine, primary-butylarsine,secondary-butylarsine, amylarsine, etc.,an arylarsine, for example,phenylarsine, etc., a stibine, such as an alkylstibine, for example,methylstibine, dimethylstibine, trimethylstibene, ethylstibine,diethylstibine, triethylstibine, propylstibine, primary-butylstibine,secondary-butylstibine, tertiary-butylstibine, etc., an arylstibine, forexample, phenylstibine, and nucleating agents of the formula:

wherein R, R and R" each represent a hydrogen atom, a halogen atom, suchas chlorine, bromine, fluorine, iodine, an alkyl group, such as methyl,ethyl, propyl, etc., an alkoxy group, such as methoxy, ethoxy, propoxy,etc. Included among the boron compound nucleating agents of theinvention are the following typical examples which are illustrative andnot intended to limit the invention:

AMINE BORANES Trimethylamine borane Diethylamine borane Triethylamineborane Tert.-butylamine borane Pyridine borane 2,6-lutidine borane POLYAMINE BORANES Ethylenediamine diborane Hydrazine diborane PHOSPHINEBORANE Dimethylphosphine borane ARSINE BORANE Dimethylarsine boraneSTIBINE BORANE Dimethylstibine borane BORAZINES EorazineN,N',N-trimethyl borazine N,N',N"-trimethoxy borazine These compoundsand their preparations have been described in the literature. Forexample, the monograph, Borax to Boranes, edited by T. Wartik, andHeinrich Ntith Hassobeyer, Berichte, vol. 93, pages 928-38 and 1078-83(1960), describe the aliphatic amine boranes.

The pyrindine and lutidine boranes are commercially available from theCallery Chemical Company, in Pittsburgh, Pennsylvania.

The phosphine boranes, the arsine boranes a-nd stibine boranes aredescribed in Miller et al. US. Patent 2,999,- 864, issued September 12,1961.

The borazines are synthesized by condensation of diborane with theappropriate nitrogen compound. For example, borazine is made bycondensing diborane with ammonia. N,N',N"-trialkyl borazine is producedby condensing diborane with the corresponding N-alkyl amine. AnN,N'-dialkyl borazine is produced by condensing diborane with a mixtureof ammonia and the appropriate N-alkylamine.

In the reversal processing of multilayer, multicolor photographicelements, the first developer forms a negative black-and-white image.Photographic elements of the multilayer, multicolor type which do notcontain color-forming couplers in the silver halide emulsion layers thenare given a selective reveral re-exposure of one silver halide emulsionlayer at a time followed by color development of the reversal exposedlayer with a color developer containing a color-forming coupler whichreacts with the oxidized p-phenylenediamine type developer to form theappropriate dye image corresponding to the positive silver image formed.After selective reversal re-exposure and color development of one layer,a second layer is selectively reversal re-exposed and color developed,then the third layer is selectively reversal re-exposed and colordeveloped. The silver images and remaining silver halide are thenremoved by bleaching and fixing to leave the three dye images. Thenucleating agents of our invention are used to advantage to eliminatethe reversal re-exposure required for the last color development step.For this purpose, the nucleating agents are either used in a nucleatingbath to which the film is contacted after the second layer is colordeveloped and before the third layer is color developed oralternatively, the nucleating agent is incorporated in the colordeveloper used to develop the third layer.

Particularly useful color films for reversal processing according to themethod of our invention are films comprising a conventional support,such as cellulose esters, glass, polyester film, polyvinyl acetal film,polycarbonate film, etc., having coated thereon at least two silverhalide layers which have been sensitized to particular regions of thespectrum. These emulsions have incorporated therein the color-formingcomponents or couplers, which combine with the oxidation products of thephotographic color developers, to produce the desired color images. Forexample, a typical color film, useful in practicing our inventioncomprises a support having coated thereon a red-sensitized photographicsilver halide emulsion having incorporated therein a coupler for thecyan image (e.g., a phenolic coupler), a greenesensitized photographicsilver halide emulsion having incorporated therein a coupler for themagenta image (e.g., pyrazolone coupler), and a bluesensitizedphotographic silver halide emulsion containing a coupler for the yellowimage (e.g., a coupler containing an open-chain ketomethylene group).The photographic element can also contain conventional interlayers andfilter layers, such as a yellow filter layer beneath the blue-sensitizedemulsion to prevent exposure by blue light to either the redorgreen-sensitized emulsion. Photographic color films of theabove-described type can be processed by a technique requiring fewersteps than the processing of color films of the multilayer, multicolortype mentioned above. For the processing of the emulsions having couplercompounds incorporated therein, it is only necessary to treat theexposed color film with the usual type of black-and-white developer forproducing a negative silver image, followed by treatment with theaqueous nucleating solution and followed by conventional color developeror alternatively, followed by treatment with the color developer towhich has been added one of" our nucleating agents.

Our nucleating baths in their simplest form comprise an aqueous solutionof the boron compound nucleating agent. The pH of the solution isconveniently adjusted by adding a suitable alkaline material, such assodium hydroxide, sodium carbonate, etc., or a suitable acidic material,such as acetic acid. Our nucleating agents are stable in aqueoussolution at pHs as low as 3 and are thus useful in the range from 3 to13, the particular level chosen depending upon the sensitometric resultsdesired.- The nucleating agents can be used to advantage at con--centrations above 1 mg. per liter. Usually they are used in the rangefrom 1 to 1,000 mg. per liter. The preferred. concentration is fromabout to 400 mg. per liter.

Similarly, color developers containing at least 1 mg.- per liter of oneof our boron compound nucleating agents-'- are used to advantage.Usually, they are used in the range from 1 to 100 mg. per liter, withthe preferred concentration from about 10 to 100 mg. per liter. Suchcolor developers may be of the type used to develop Kodachrome film(that is, the developer contains the color-forming coupler) or of thetype color developer used to process coupler incorporated silver halideemulsion layers.

The following typical examples will further illustrate the nucleatingstep or combined nucleating and color development step of our invention.1

Example 1 A photographic multilayer color element containing threedifferentially sensitized photographic silver halide emulsion layers,having color-forming couplers incorporated therein, was exposed to astep wedge in a sensitometer. The exposed color film Was then developedin a developer having the following composition:

Water to make 1.0 liter.

The element was then washed with water and treated in a hardening bathhaving the composition:

G. Potassium chrome alum crystals 30.0 Water to make 1.0 liter. Theelement was then treated for 1 minute in a nucleating bath having thecomposition:

G. Sodium hexametaphosphate 1.0 Sodium hydroxide 1.5 Tert.-butylamineborane 0.4

Water to make 1.0 liter.

The element was then treated in a color developer having the followingcomposition:

Benzyl alcohol, cc. 6.0 Sodium hexametaphosphate, g. 2.0 Sodium sulfite,anhydrous, g. 5.0 Trisodium phosphate, g. 40.0 Potassium bromide, g.0.25 0.1% solution of potassium iodide, cc. 10.0 Sodium hydroxide, g.6.5

Color developer, g. 11.33 Ethylenediamine sulfate, g. 7.8 Citrazinicacid, g. 1.5 Water to make 1.0 liter.

N ethyl N (fi-methanesulton mld h 1 toluidlne sesqulsulfate monohydmte,ct y m The element was then washed thoroughly with water and treated ina clearing and fixing bath having the following composition:

G. Sodium thiosulfate 150.0 Sodium bisulfite 20.0

Water to make 1.0 liter.

The element was then treated in a bleach bath having the followingcomposition:

G. Potassium dichromate 5.0 Potassium ferricyanide 70.0 Potassiumbromide 20.0

Water to make 1.0 liter.

The element was again washed and treated once again with the clearingand fixing bath identified above. The element was again washed andtreated in a stabilizing bath having the following composition:

Formaldehyde (37% by weight), cc. 7.0 Dispersing agent,** g. 0.5 Waterto make 1.0 liter.

Such as Triton-X 100, Le, an alkylaryl polyether alcohol (octylphenoxypolyethoxy ethanol).

Another piece of the same multilayer color element was given the sameexposure and process as described above except that the usual whitelight reversal re-exposure was used in place of the nucleating bath ofour invention.

Still another piece of the same multilayer color element was given thesame exposure and process except that no nucleating bath or reversalre-exposure was used.

A comparison of the processed elements showed that the element given ournucleating bath treatment had sensitometric quality comparable to theelement given the reversal re-exposure. The element that receivedneither treatment with the nucleating bath or reversal re-exposureduring the processing was unsatisfactory.

Example 2 Photographic multilayer color elements such as were used inExample 1 were exposed and processed using the nucleating bath in placeof reversal re-exposure but substituting for the tert.-butylamineborane, trimethylamine borane, diethylamine borane, triethylamineborane, pyridine borane, and 2,6-lu-tidine borane.

The processed elements showed that each of these nucleating baths gavegood sensitometric results.

Example 3 Photographic multilayer color elements such as were describedin Example 1 were exposed to a step wedge in a sensitometer in the usualWay. These were processed as described in Example 1 with the followingexceptions, the boron compound nucleating agent was added to the colordeveloper solution to give a concentration of 0.10 gram per liter, noseparate nucleating bath was used (nor was reversal re-exposure used).Good sensitometric results were obtained by processing color elementsthrough processes in which trirnethylamine borane, diethylamine borane,triethylamine borane, tert.-b-utylamine borane, pyridine borane and2,6-lutidine borane were used as the nucleating agent in the colordeveloper. Although the pH of these developers was at 11.60 and lower,the boron compounds showed no evidences of decomposition.

Similarly, other boranes of our invention, such as the phosphine,arsine, and stibine boranes, etc., and the borazines and substitutedborazines of our invention can be used to advantage.

Color development, as described in the above examples, can be carriedout using any of the Well known color-forming developers which arecapable of coupling with the color-forming components or couplers.Particularly useful color-forming developers are the phenylenediaminesand substituted derivatives thereof. Typical of such color-formingdevelopers are the sulfonamidosubstituted p-phenylenediamines disclosedin Weissberger US. Patent 2,548,574, issued April 10, 1951, thesubstituted p-phenylenediamines disclosed in Wei-ssberger et al. US.Patents 2,552,2402, issued May 8, 1951, and the substitutedp-phenylenediamines disclosed in Weissberger et al. US. Patent2,566,271, issued August 28, 1951. Other phenylenediamine color-formingdevelopers can be employed to like advantage in the process of ourinvention.

Similarly, our nucleating agents are used in processes for multilayer,multicolor type films. They are also used in black-and-white reversalprocesses in aqueous nucleating baths to eliminate the need for reversalreexposure. In a black-and-white process, the negative development isfollowed by a water wash, a bleach, clearing bath, water wash, aqueousnucleating bath and positive development.

Our nucleating agents are valuable for use in nucleating baths ordirectly in color developers used in processing multilayer colorphotographic elements, since their use eliminates the need for reversalre-exposure. Our nucleating agents are especially valuable in processingcolor photographic elements which contain the colorforming couplers inthe emulsion layers because they are stable in aqueous solutions at muchlower pHs than are some of the prior art nucleating agents. Some of theprior art nucleating agents when used at pH levels where they arestable, have a strong tendency to produce undesirable stains in theprocessed elements. Color photographic elements processed by ourreversal process have good sensitometric characteristics.

The invention has been described in detail with particular reference topreferred embodiments thereof but it will be understood that variationsand modifications can i be effected within the spirit and scope of theinvention as described hereinabove and as defined in the appendedclaims.

We claim:

'1. In a method of producing a photographic color reproductioncomprising exposing to a colored image a photographic element containingat least two photographic silver halide emulsion layers which have beendifferentially sensitized to different spectral regions, developing saidphotographic element to a negative blackand-white image by treatmentwith a photographic blackand-white developer, contacting saidphotographic element with a nucleating agent for sufiicient time tonucleate previously unexposed silver halide and render it developable toa visible image upon contact with a second developer, and developingsaid photographic element in a photographic color developer solution inthe presence of a color-forming compound which couples with theoxidation products of said photographic color developer to produce acolored image, the step comprising nucleating said previously unexposedsilver halide by contacting said photographic element with an aqueoussolution of a boron compound nucleating agent selected from those havingthe formula:

(I) ZBH wherein Z represents a member selected from the class consistingof ammonia, an amine, an ethylenediamine borane, a hydrazine borane, aphosphine, an arsine, and a stibine, and the formula:

wherein R, R, and R each represent a member selected from the classconsisting of the hydrogen atom, a halogen atom, an alkyl group, and analkoxy group, said aqueous solution having a pH in the range from about2 to 14, and containing at least 1 mg. of said boron compound per literof solution.

2. In a method of reproducing a photographic color reproductioncomprising exposing to a colored image a photographic element comprisinga support having coated thereon three photographic silver halideemulsion layers, one of said layers being sensitive to the red region ofthe spectrum and having dispersed therein a cyanimage-forrning coupler,one of said layers being sensitive to the green region of the spectrumand containing a magenta-imageforming coupler, and a third one of saidlayers being sensitive to the blue region of the spectrum and containinga yellow-image-forming coupler, developing said photographic element ina photographic black-and-white developer to produce a negative image,contacting said photographic element with a nucleating agent for asufficient time to nucleate the previously unexposed silver halide andrender it developable to a Visible image by developing said element in aphotographic phenylenediamine color developer to produce colored imagesbearing a complementary relationship to the color in the original beingreproduced, contacting said photographic element with a photographicclearing and fixing bath, contacting said element with an oxidizing bathto remove residual silver salts from said photographic silver halideemulsion layers, the step of nucleating said previously unexposed silverhalide by contacting said photographic element with an aqueous solutionof a boron compound nucleating agent selected from those having theformula:

(I) ZBH wherein Z represents a member selected from the class consistingof ammonia, an amine, an ethylenediamine borane, a hydrazine borane, aphosphine, an arsine, and.

a stibine, and the formula: (I III /N II1I3 Iii-H R-N N-R B wherein R,R, and R each represent a member selected from the class consisting ofthe hydrogen atom, a halogen atom, an alkyl group, and an alkoxy group,said aqueous solution having a pH in the range from about 2 to 14, andcontaining at least 1 mg. of said boron compound per liter of solution.

3. A photographic reversal process of claim 2 in which the step ofnucleating the photographic element is accomplished by treating saidelement with the aqueous solution of the boron compound nucleating agentbefore contacting said film with the photographic color developersolution.

4. A photographic reversal process of claim 2 in which the step ofnucleating and color developing the photographic element is accomplishedby treating said element in the photographic color developer to whichhas been added at least 1 mg. of the boron compound nucleating agent perliter of said developer 5. A photographic reversal process of claim 2 inwhich the boron compound nucleating agent is tert-butylamine borane.

6. A photographic reversal process of claim 2 in which the boroncompound nucleating agent is pyridine borane.

7. A photographic reversal process of claim 2 in which the boroncompound nucleating agent is -2,6-lutidine borane.

8. A photographic reversal process of claim 2 in which the boroncompound nucleating agent is dimethylamine borane.

9. A photographic reversal process of claim 2 in which the boroncompound nucleating agent is trie'thylamine borane.

References Cited by the Examiner UNITED STATES PATENTS 2,150,704 3/1939Ville 96 59 2,159,466 5/1939 Wilmanns et a1. 96 59 2,588,982 3/1952 Ives96-94 2,984,567 5/1961 Henn et al. 96 59 2,999,864 9/1961 Miller et al.260-240 NORMAN G. TORCHIN, Primary Examiner.

2. IN A METHOD OF REPRODUCING A PHOTOGRAPHIC COLOR REPRODUCTIONCOMPRISING EXPOSING TO A COLORED IMAGE A PHOTOGRAPHIC ELEMENT COMPRISINGA SUPPORT HAVING COATED THEREON THREE PHOTOGRAPHIC SILVER HALIDEEMULSION LAYERS, ONE OF SAID LAYERS BEING SENSITIVE TO THE RED REGION OFTHE SPECTRUM AND HAVING DISPERSED THEREIN A CYANIMAGE-FORMING COUPLER,ONE OF SAID LAYERS BEING SENSITIVE TO THE GREEN REGION OF THE SPECTRUMAND CONTAINING A MAGENTA-IMAGE-FORMING COUPLER, AND A THIRD ONE OF SAIDLAYERS BEING SENSITIVE TO THE BLUE REGION OF THE SPECTRUM AND CONTAININGA YELLOW-IMAGE-FORMING COUPLER, DEVELOPING SAID PHOTOGRAPHIC ELEMENT INA PHOTOGRAPHIC BLACK-AND-WHITE DEVELOPER TO PRODUCE A NEGATIVE IMAGE,CONTACTING SAID PHOTOGRAPHIC ELEMENT WITH A NUCLEATING AGENT FOR ASUFFICIENT TIME TO NUCLEATE THE PREVIOUSLY UNEXPOSED SILVER HALIDE ANDRENDER IT DEVELOPABLE TO A VISIBLE IMAGE BY DEVELOPING SAID ELEMENT INPHOTOGRAPHIC PHENYLENEDIAMINE COLOR DEVELOPER TO PRODUCE COLORED IMAGESBEARING A COMPLEMENTARY RELATIONSHIP TO THE COLOR IN THE ORIGINAL BEINGREPRODUCED, CONTACTING SAID PHOTOGRAPHIC ELEMENT WITH A PHOTOGRAPHICCLEARING AND FIXING BATH, CONTACTING SAID ELEMENT WITH AN OXIDIZING BATHTO REMOVE RESIDUAL SILVER SALTS FROM SAID PHOTOGRAPHIC SILVER HALIDEEMULSION LAYERS, THE STEP OF NUCLEATING SAID PREVIOUSLY UNEXPOSED SILVERHALIDE BY CONTACTING SAID PHOTOGRAPHIC ELEMENT WITH AN AQUEOUS SOLUTIONOF A BORON COMPOUND NUCLEATING AGENT SELECTED FROM THOSE HAVING THEFORMULA: (I) ZBH3 WHEREIN Z REPRESENTS A MEMBER SELECTED FROM THE CLASSCONSISTING OF AMMONIA, AN AMINE, AN ETHYLENEDIAMINE BORANE, A HYDRAZINEBORANE, A PHOSPHINE, AN ARSINE, AND A STIBINE, AND THE FORMULA: